But all the continuity on display shouldn’t overshadow the most important thing about Turn Left. That it was an absolutely phenomenal piece of television.

First things first. Catherine Tate. Over the course of my involvement with Behind the Sofa, I’ve been happy to admit how wrong I was with regards to her returning. Yes, we’d all heard about the RSC training, but after suffering through that pantomime performance in The Runaway Bride, it was clear a lot of fans - myself included - feared another Bonnie.

How wrong we were.

This was a tremendous turn from Tate, as we see a very different Donna - one clearly undermined and almost downtrodden by her mother’s disappointment in her. Who remains wrapped up in her own little world, even as the rest of the universe collapses in around her. Donna not meeting the Doctor might have killed him physically, but it also killed her spirit.

Her finest scene in this episode? There’s so many to pick from, but for me it’s that moment when realisation slowly dawns, as the foreign family sharing the refugee home in Leeds is sent to a ‘labour camp’, what that actually means besides her own family having more room.

She’s never been less than great this season, and here she was on another planet

You see it in her eyes, the shattering of that selfish reality she’s wrapped around herself, and it’s replacement with the harshness of their new, Threads-lite environment.

Given the hype about Rose’s return, this is very much Donna’s story and Catherine’s performance. Partners in Crime aside, she’s never been less than great this season, and here she was on another planet.

As with the previous Doctor-lite episodes, the chance to do something experimental and out-there drew the best from a talented scribe. Russell’s script, revisiting the world without Donna’s influence on the Doctor, was a genuine joy, taking the big Earth-based set-pieces of the last two seasons and turning them up to 11. It almost redeemed the Voyage of the Damned. What was a ridiculous premise - a spaceship replica of the Titanic hurtling towards Buckingham Palace - became a chilling, hideous concept, as a mushroom cloud rose on the horizon.

Graham Harper’s skilled direction also helped. Joe Ahearne, Euros Lyn and Harper have helped define a visual style for these key episodes, and as with Utopia last year Harper’s energy takes a great script and makes it rollercoaster stuff. Can you imagine what this man would be like doing a season of 24? There’s not enough adrenaline in the world to keep up.

Often, in fact, there was a feeling of Sam Raimi about the direction, especially as the Bad Wolf revelation kicked in, and we crash zoomed into the posters and banners around the market, each one hammering home the point. Harper’s due his bus pass in two years - let’s hope the producers don’t pension him off prematurely.

So that was the good - and let’s not be mistaken, there was lots of good to go around here. But there were two big problems with the episode. Two huge problems. Two massive, ginormous problems.

We all know the Doctor Who stories where a pisspoor monster model has come close to ruining things

Specifically, the oversized beetle. And Billie Piper’s teeth.

So let’s take the former first. We all know the Doctor Who stories where a truly pisspoor monster model has come close to ruining things. By and large, most shows get away with it, but the same time these moments have an effect. They serve, even just for an instant, to take you out of the moment. It’s breaking kayfabe. Yes, we already know it’s not real, it’s just a fiction, but getting it hammered home like that has a corrosive effect.

The giant rat in The Talons of Weng-Chiang is the nearest analogue to Turn Left’s beetle. Just a big, ugly, dumb, fake moment, where the ambition and concepts of the script are largely let down by the production’s limitations. And the reveal of the beetle is the same. It just looks rubbish. It looks like the sort of prop they’d use to dress the set on I’m A Celebrity... no, worse - On Safari.

As for the second problem - what the hell happened? Seriously? Charlie Brooker on Screenwipe talked of a great game you can play with Billie Piper’s face, trying to work out what part is the biggest. But the truth, the answer, is that it’s plainly her teeth. Somewhere between Doomsday and Turn Left, La Piper’s teeth seem to have grown an inch, leaving her with a Simpsons overbite and Langford lisp.

Piper’s performance was... interesting. She talked in Confidential and during interviews of having a crisis of confidence going into the part, and having to buy a bunch of box-sets to relearn the character again. Unfortunately, it seems to be the box set of Secret Diary of a Call Girl rather than the chavvy saarf Laaahndaaner that we dumped on a beach in Norway (or Wales) last time.

She wasn’t bad, by any stretch. And since the character was supposed to have moved forward, clearly, then it makes sense that she sounds different. But what was notable was how pale a performance it was when put up against Tate. Piper was seen as a revelation when she joined the show initially, for a generation used to seeing her singing, dancing and getting hammered with Christopher Evans on a grand tour of the world’s best public houses.

In fact, one of the harshest, and most unfair, criticisms of Freema Agyeman was that she was no Billie Piper. Well, on this evidence, Billie’s no Catherine Tate. And that’s a phrase I never envisaged writing.

SFX’s smouldering sex kitten of science fiction, Jayne Nelson, wrote on her own blog how this episode was the most nu-Who has ever felt like Buffy and I can see where she’s coming from - specifically The Wish, where we see life in Sunnyvale if Buffy had never arrived.

But what’s remarkable too is how unafraid the episode - and the show itself, to an extent - is to embrace itself and it’s other franchises, despite the age and demographic gap involved. So we get the Torchwood team and Sarah Jane’s adventurers namechecked casually, as if everyone should know exactly who they are. We get references to the Trickster and his brigade, from The Sarah Jane Adventures and the Doctor Who website.

And most importantly we get the feeling that Russell has turned this show, rather than a franchise for the BBC to milk and exploit with lots of spin-offs, into a remarkable, cohesive world where everything that happens has implications, even if it’s years down the line on another branch of the line. It feels almost like a reward for paying attention all these years.

Still, it all sets up perfectly for next week’s episode, which judging by the throw forward we got at the end of Turn Left, will be An Audience Without Craig Hinton. Is Doctor Who going out on a high? You bet.

But all the continuity on display shouldn’t overshadow the most important thing about Turn Left. That it was an absolutely phenomenal piece of television.

First things first. Catherine Tate. Over the course of my involvement with Behind the Sofa, I’ve been happy to admit how wrong I was with regards to her returning. Yes, we’d all heard about the RSC training, but after suffering through that pantomime performance in The Runaway Bride, it was clear a lot of fans - myself included - feared another Bonnie.

How wrong we were.

This was a tremendous turn from Tate, as we see a very different Donna - one clearly undermined and almost downtrodden by her mother’s disappointment in her. Who remains wrapped up in her own little world, even as the rest of the universe collapses in around her. Donna not meeting the Doctor might have killed him physically, but it also killed her spirit.

Her finest scene in this episode? There’s so many to pick from, but for me it’s that moment when realisation slowly dawns, as the foreign family sharing the refugee home in Leeds is sent to a ‘labour camp’, what that actually means besides her own family having more room.

She’s never been less than great this season, and here she was on another planet

You see it in her eyes, the shattering of that selfish reality she’s wrapped around herself, and it’s replacement with the harshness of their new, Threads-lite environment.

Given the hype about Rose’s return, this is very much Donna’s story and Catherine’s performance. Partners in Crime aside, she’s never been less than great this season, and here she was on another planet.

As with the previous Doctor-lite episodes, the chance to do something experimental and out-there drew the best from a talented scribe. Russell’s script, revisiting the world without Donna’s influence on the Doctor, was a genuine joy, taking the big Earth-based set-pieces of the last two seasons and turning them up to 11. It almost redeemed the Voyage of the Damned. What was a ridiculous premise - a spaceship replica of the Titanic hurtling towards Buckingham Palace - became a chilling, hideous concept, as a mushroom cloud rose on the horizon.

Graham Harper’s skilled direction also helped. Joe Ahearne, Euros Lyn and Harper have helped define a visual style for these key episodes, and as with Utopia last year Harper’s energy takes a great script and makes it rollercoaster stuff. Can you imagine what this man would be like doing a season of 24? There’s not enough adrenaline in the world to keep up.

Often, in fact, there was a feeling of Sam Raimi about the direction, especially as the Bad Wolf revelation kicked in, and we crash zoomed into the posters and banners around the market, each one hammering home the point. Harper’s due his bus pass in two years - let’s hope the producers don’t pension him off prematurely.

So that was the good - and let’s not be mistaken, there was lots of good to go around here. But there were two big problems with the episode. Two huge problems. Two massive, ginormous problems.

We all know the Doctor Who stories where a pisspoor monster model has come close to ruining things

Specifically, the oversized beetle. And Billie Piper’s teeth.

So let’s take the former first. We all know the Doctor Who stories where a truly pisspoor monster model has come close to ruining things. By and large, most shows get away with it, but the same time these moments have an effect. They serve, even just for an instant, to take you out of the moment. It’s breaking kayfabe. Yes, we already know it’s not real, it’s just a fiction, but getting it hammered home like that has a corrosive effect.

The giant rat in The Talons of Weng-Chiang is the nearest analogue to Turn Left’s beetle. Just a big, ugly, dumb, fake moment, where the ambition and concepts of the script are largely let down by the production’s limitations. And the reveal of the beetle is the same. It just looks rubbish. It looks like the sort of prop they’d use to dress the set on I’m A Celebrity... no, worse - On Safari.

As for the second problem - what the hell happened? Seriously? Charlie Brooker on Screenwipe talked of a great game you can play with Billie Piper’s face, trying to work out what part is the biggest. But the truth, the answer, is that it’s plainly her teeth. Somewhere between Doomsday and Turn Left, La Piper’s teeth seem to have grown an inch, leaving her with a Simpsons overbite and Langford lisp.

Piper’s performance was... interesting. She talked in Confidential and during interviews of having a crisis of confidence going into the part, and having to buy a bunch of box-sets to relearn the character again. Unfortunately, it seems to be the box set of Secret Diary of a Call Girl rather than the chavvy saarf Laaahndaaner that we dumped on a beach in Norway (or Wales) last time.

She wasn’t bad, by any stretch. And since the character was supposed to have moved forward, clearly, then it makes sense that she sounds different. But what was notable was how pale a performance it was when put up against Tate. Piper was seen as a revelation when she joined the show initially, for a generation used to seeing her singing, dancing and getting hammered with Christopher Evans on a grand tour of the world’s best public houses.

In fact, one of the harshest, and most unfair, criticisms of Freema Agyeman was that she was no Billie Piper. Well, on this evidence, Billie’s no Catherine Tate. And that’s a phrase I never envisaged writing.

SFX’s smouldering sex kitten of science fiction, Jayne Nelson, wrote on her own blog how this episode was the most nu-Who has ever felt like Buffy and I can see where she’s coming from - specifically The Wish, where we see life in Sunnyvale if Buffy had never arrived.

But what’s remarkable too is how unafraid the episode - and the show itself, to an extent - is to embrace itself and it’s other franchises, despite the age and demographic gap involved. So we get the Torchwood team and Sarah Jane’s adventurers namechecked casually, as if everyone should know exactly who they are. We get references to the Trickster and his brigade, from The Sarah Jane Adventures and the Doctor Who website.

And most importantly we get the feeling that Russell has turned this show, rather than a franchise for the BBC to milk and exploit with lots of spin-offs, into a remarkable, cohesive world where everything that happens has implications, even if it’s years down the line on another branch of the line. It feels almost like a reward for paying attention all these years.

Still, it all sets up perfectly for next week’s episode, which judging by the throw forward we got at the end of Turn Left, will be An Audience Without Craig Hinton. Is Doctor Who going out on a high? You bet.